Generally, a bridge includes piers, girders which are spaced from each other in a widthwise direction of the bridge and connected to the piers at both their ends, and floor slabs formed on the girders.
Typically the floor slab is formed by installing the girders in a manner to be supported on and stretched between the piers, installing a mould for the floor slab on the girders, pouring concrete into the mould, and curing the concrete.
The bridge is also provided with side barriers which prevent vehicles running along the bridge from slipping off and falling down from the bridge.
Therefore, the construction process of the floor slab for a bridge is complicated and involves difficult work. Further, it takes a long time due to concrete placement and curing.
In addition, the work of constructing the floor slab for a bridge incurs a lot of labor costs, contributing to a large increase in the total cost of bridge construction.
Besides the cost problem, the above-described floor slab construction method has a more serious problem in that it is difficult to apply to construction of skew bridges, curved bridges, and the like.
That is, the side barriers are formed by installing moulds on site at both ends of the upper surface of the constructed floor slab after completing the construction of the floor slab, pouring concrete into the moulds, and curing the concrete. For this reason, the formation of the side barriers is another factor of increasing the time period for bridge construction.
Furthermore, since the side barriers cannot interact with the floor slab at all, the side barriers do not function as a structure which resists against an external load in the sense of dynamics but function as a structure which adds weight to the bridge.